Preform and a Mold Stack for Producing the Preform

ABSTRACT

According to embodiments of the present invention, there is provided a preform and a mold stack for producing the preform. For example, there is provided a preform suitable for subsequent blow-molding. The preform comprises a neck portion; a gate portion; and a body portion extending between said neck portion and said gate portion; the gate portion being associated with a substantially conical shape. In an example embodiment, the substantially conical shape is selected such that to substantially homogenize angle of refraction of rays used during a re-heating stage of a blow-molding process.

FIELD OF THE INVENTION

The present invention generally relates to, but is not limited to, amolding systems and processes, and more specifically the presentinvention relates to, but is not limited to, a preform and a mold stackfor producing the preform

BACKGROUND OF THE INVENTION

Molding is a process by virtue of which a molded article can be formedfrom molding material by using a molding system. Various molded articlescan be formed by using the molding process, such as an injection moldingprocess. One example of a molded article that can be formed, forexample, from polyethylene terephthalate (PET) material is a preformthat is capable of being subsequently blown into a beverage container,such as, a bottle and the like.

As an illustration, injection molding of PET material involves heatingthe PET material (ex. PET pellets, PEN powder, PLA, etc.) to ahomogeneous molten state and injecting, under pressure, the so-meltedPET material into a molding cavity defined, at least in part, by afemale cavity piece and a male core piece mounted respectively on acavity plate and a core plate of a mold. The cavity plate and the coreplate are urged together and are held together by clamp force, the clampforce being sufficient to keep the cavity and the core pieces togetheragainst the pressure of the injected PET material. The molding cavityhas a shape that substantially corresponds to a final cold-state shapeof the molded article to be molded. The so-injected PET material is thencooled to a temperature sufficient to enable ejection of the so-formedmolded article from the mold. When cooled, the molded article shrinksinside of the molding cavity and, as such, when the cavity and coreplates are urged apart, the molded article tends to remain associatedwith the core piece. Thereafter, the molded article can be ejected offof the core piece by use of one or more ejection structure. Ejectionstructures are known to assist in removing the molded articles from thecore halves. Examples of the ejection structures include stripperplates, stripper rings and neck rings, ejector pins, etc.

With reference to FIG. 1, a preform 100 is depicted, the preform 100being an example of a typical prior art preform. The preform 100consists of a neck portion 102, a gate portion 106 and a body portion104 extending between the neck portion 102 and the gate portion 106. Thegate portion 106 is associated with a substantially spherical shape thatterminates in a vestige portion 108.

U.S. Pat. No. 4,432,530 issued to Marcinek on Feb. 21, 1984 discloses amold and core rod combination for forming a plastic parison forstretch/blowing into a plastic bottle comprising a core rod with an endmated to the mold so as to permit formation of a parison with a flat onthe bottom and having a sharp taper from said flat to the sidewall ofthe parison. The core rod is preferably shaped to include a shoulderhaving a substantially straight outer wall at the mouth end of theparison mold, and constructed and arranged with the mold to permitdeposit of additional plastic at the inner wall of the shoulder of theparison. The design of the mated mold and core rod combination is basedon the recognition that in a continuous bottle forming process aparticular area of the parison can be made hotter or cooler byincreasing or decreasing the thickness of that area of the parison.Parisons formed with the disclosed mold-core rod combination permit adeeper and longer stretch of the parison without tearing or deformationof the parison bottom or deformation or wrinkling at the shoulder of thefinished bottle while providing essential wall strength.

U.S. Pat. No. 4,959,006 issued to Feddersen et al. on Sep. 23, 1990discloses a mold-core rod combination for producing a plastic preformfor forming blow molded plastic bottles which comprises: a neck portiondefining an opening; a tubular sidewall portion depending therefrom; andan integral base structure depending from the tubular sidewall portionto a closed end; the preform having an outside wall face and an insidewall face with one of these in the base structure having integrallyformed thereon a plurality of filets, extending longitudinally of thepreform and defining a continuous reinforcing ring of varying thicknessspaced from the closed end and circumscribing the base structure,wherein the filets decrease progressively in width and radial thicknessat least from the reinforcing ring toward the closed end. The preform iscapable of forming a blow molded plastic bottle with a bottom portionhaving a continuous reinforcing ring of circumferentially continuousradially extending alterations in wall thickness with a regularlyundulating cross-section along the circumference. Preferably the filetsare integral with the inside wall face.

SUMMARY OF THE INVENTION

According to a first broad aspect of the present invention, there isprovided a preform suitable for subsequent blow-molding. The preformcomprises a neck portion; a gate portion; and a body portion extendingbetween the neck portion and the gate portion; the gate portion beingassociated with a substantially conical shape.

According to a second broad aspect of the present invention, there isprovided a mold stack. The mold stack comprises a core insert fordefining an internal surface of a preform; a split mold insert pair fordefining an external surface of a neck portion of the preform; a cavityinsert for defining the external surface of a body portion of thepreform; a gate insert for defining the external surface of a gateportion of the preform; the core insert and the gate insert beingconfigured to cooperate, in use, to define the gate portion of thepreform having a first substantially conical shape.

According to a third broad aspect of the present invention, there isprovided a core insert for defining, in use, a portion of a preform, thepreform including a neck portion, a gate portion and a body portionextending therebetween. The core insert comprises a first cavitydefining portion having a gate defining portion which has substantiallyconical shape, the substantially conical shape so selected such that tohomogenize angle of refraction of rays used during a re-heating stage ofa blow-molding process of the preform within the gate portion.

According to a fourth broad aspect of the present invention, there isprovided a gate insert for defining, in use, a portion of a preform, thepreform including a neck portion, a gate portion and a body portionextending therebetween. The gate insert comprises a second cavitydefining portion having a substantially inverted conical shape thesubstantially conical cone shape so selected such that to homogenizeangle of refraction of rays used during a re-heating stage of ablow-molding process of the preform within the gate portion.

According to another broad aspect of the present invention, there isprovided a method of producing at least a portion of a mold stack. Themethod comprises selecting a shape for a gate portion of a preformsuitable for blow-molding, the shape so selected as to at leastsubstantially homogenize angle of refraction of at least some of a setof rays during re-heating stage of a blow-molding process; manufacturingthe at least a portion of the mold stack to include the shape.

According to yet another broad aspect of the present invention, there isprovided preform suitable for subsequent blow-molding. The preformcomprises a neck portion, a gate portion; and a body portion extendingbetween the neck portion and the gate portion; the gate portion beingassociated a shape so selected such that to substantially homogenizeangle of refraction of rays used during a re-heating stage of ablow-molding process.

These and other aspects and features of non-limiting embodiments of thepresent invention will now become apparent to those skilled in the artupon review of the following description of specific non-limitingembodiments of the invention in conjunction with the accompanyingdrawings.

DESCRIPTION OF THE DRAWINGS

A better understanding of the non-limiting embodiments of the presentinvention (including alternatives and/or variations thereof) may beobtained with reference to the detailed description of the non-limitingembodiments along with the following drawings, in which:

FIG. 1 depicts a cross section view of a preform 100 implemented inaccordance with known techniques.

FIG. 2 schematically depicts the preform 100 of FIG. 1 during are-heating stage of a blow-molding process, implemented in accordancewith known techniques.

FIG. 3 depicts a cross section view of a preform 300 implemented inaccordance with a non-limiting embodiment of the present invention.

FIG. 4 depicts a cross section view of a preform 400 implemented inaccordance with another non-limiting embodiment of the presentinvention.

FIG. 5 schematically depicts a portion of the preform 300 during there-heating stage of the blow-molding process, similar to that of FIG. 2.

FIG. 6 depicts a cross-section view of a mold stack 600 configured toproduce the preform 300 of FIG. 3, implemented according to anon-limiting embodiment of the present invention.

FIG. 7 is a side view of a core insert 602 of the mold stack 600 of FIG.6, implemented according to a non-limiting embodiment of the presentinvention.

FIG. 8 is a cross-section view of a gate insert 608 of the mold stack600 of FIG. 6, implemented according to a non-limiting embodiment of thepresent invention.

FIG. 9 depicts a cross section view of a preform 900 implemented inaccordance with yet another non-limiting embodiment of the presentinvention.

FIG. 10 depicts a cross-section view of a portion of a mold stack 1000configured to produce the preform 900 of FIG. 9, implemented accordingto a non-limiting embodiment of the present invention.

The drawings are not necessarily to scale and may be illustrated byphantom lines, diagrammatic representations and fragmentary views. Incertain instances, details that are not necessary for an understandingof the embodiments or that render other details difficult to perceivemay have been omitted.

DETAILED DESCRIPTION OF EMBODIMENTS

Inventors have appreciated that there exists a problem with knowndesigns of preforms 100. With reference to FIG. 2, one such problem willnow be illustrated in greater detail. FIG. 2 schematically illustratesthe preform 100 of FIG. 1 during a re-heating stage of blow-moldingprocess during which the preform 100 is formed into a final-shapedproduct. The re-heating stage is typically implemented duringstretch-blow molding process, which is carried out subsequent to amolding operation to transform the preform 100 into a final-shapedarticle (such as a bottle and the like). The stretch-blow molding can beconveniently executed in a stretch-blow molding machine (not depicted).

Within the illustration of FIG. 2, there are provided a source of energy202 and a reflector 204. Generally speaking, the purpose of the sourceof energy 202 and the reflector 204 is to re-heat the preform 100 to arequired temperature, the required temperature being sufficient tore-shape the so-heated preform 100 into the final-shaped article.

The source of energy 202 comprises a plurality of emitters 203. Theplurality of emitters 203 can be implemented in several variations, butwithin the specific non-limiting embodiment being presented herein, theplurality of emitters 203 can comprise a plurality of infrared lightemitters. The plurality of emitters 203 can emit heat energy, such asfor example, in a form of a set of infrared light rays 206 or the like.The set of infrared light rays 206 penetrates the preform 100 and,subsequently, gets reflected by the reflector 204 (such as, a mirror orthe like), as a set of reflected infrared light rays 208. The reflector204 is typically used to increase efficiency of the re-heating stage.

In alternative non-limiting embodiment of the present invention theplurality of emitters 203 can be configured to emit energy at frequencyother than infrared. Accordingly, the set of infrared light rays 206will be referred herein below from time to time as rays 206 to captureother alternatives for the type of energy used.

Due, at least partially, to the spherical shape of the gate portion 106and, as the result, variable angle of refraction of the set of infraredlight rays 206, which is particularly acute in the gate portion 106, asub-set of infrared light rays 210 is created. The sub-set of infraredlight rays 210 is not reflected (or is reflected at a larger angle) bythe reflector 204, which significantly decreases the re-heatingefficiency within the gate portion 106 and/or causes the re-heating tobe uneven (i.e. variable) along the length of the gate portion 106. Onecommon solution has been to create a subset of the plurality of emitters203 that are located proximate to the gate portion 106, the subset ofthe plurality of emitters 203 being categorized by having higher powerthan the rest of the plurality of emitters 203. As one can appreciate,this results in additional energy consumption and additional costs,which is not entirely satisfactory from the overall operation andenvironmental perspectives.

Reference is now made to FIG. 3, which depicts a preform 300 implementedaccording to a non-limiting embodiment of the present invention. Thepreform 300 consists of a neck portion 302, a gate portion 306 and abody portion 304 extending between the neck portion 302 and the gateportion 306. The neck portion 302 and the body portion 304 can beimplemented in a substantially similar manner to the neck portion 102and the gate portion 106 of the preform 100 of FIG. 1.

Within these embodiments of the present invention, the gate portion 306is associated with a substantially conical shape that terminates in avestige portion 308. It is worthwhile noting that the vestige portion308 delimits a lower terminal point of the conical shape of the gateportion 306. Size of the vestige portion 308 can substantiallycorrespond to size of an orifice of a hot runner nozzle (not depicted).Within the embodiment of FIG. 3, the gate portion 306 is associated witha substantially uniform wall thickness “W”, but this not need be so inevery embodiment of the present invention (as will be illustrated hereinbelow).

Within the embodiment of FIG. 3, the conical shape of the gate portion306 is associated with an angle “α” defined between an imaginary centralline 310 (the imaginary central line 310 passing through a longitudinalaxis of the preform 300) and an internal surface of the conical shape ofthe gate portion 306. In some embodiments of the present invention, theangle “α” can be so selected as to substantially homogenize the angle ofrefraction along the gate portion 306 during the re-heating stage of theblow-molding process. It has been found, for example, that thesubstantially conical shape of the gate portion 306 leads to morehomogenous angle of refraction (and, therefore, more homogenous level ofabsorbance and re-heating) and, generally speaking, the smaller theangle “α” selected, the better homogeneity of angle of refraction (and,therefore, re-heating) is achieved.

In alternative non-limiting embodiments of the present invention, theangle “α” can be selected further taking into account rate of fillingthat the angle “α” will lead to and/or amount of material that will beused based on the angle “α”. As an example, the smaller the angle “α”selected, the smaller the pressure drop associated with the gate area ofthe molding cavity during the filling stage and, therefore, the fasterthe associated filling rates. By the same token, the smaller the angle“α” selected, the less material will be used to fill the gate area ofthe molding cavity.

Accordingly, in some embodiments of the present invention, the angle “α”can be selected taking into account some or all of (i) refraction indexof a particular molding material being used, (ii) rate of filling thatthe angle “α” will lead to; and (iii) amount of material that will beused based on the angle “α”. Accordingly, within these embodiments ofthe present invention, the angle “α” can be calculated as function ofall or some of (i) the refraction index of the molding material, (ii)weight of the molding material to be used (i.e. stretch function of theangle “α” and the wall thickness resultant from the angle “α”), (iii)the filling rate.

For example, in case of PET, the angle “α” can be selected from a rangeof between, for example, approximately 10 degrees and approximately 90degrees. In a specific non-limiting embodiment of the present invention,in case of PET, the angle “α” can be selected from a range of between,for example, approximately 37 degrees and approximately 40 degrees. Inanother specific non-limiting embodiment of the present invention, incase of PET, the angle “α” can be selected from a range of between, forexample, approximately 40 degrees and approximately 60 degrees. In aparticular specific non-limiting example, the angle “α” used can be 37degrees. Naturally, any other angle “α” based on the refraction index ofthe particular molding material or any other factors discussed hereinabove can be used.

Reference is now made to FIG. 4, which depicts a preform 400 implementedaccording to another non-limiting embodiment of the present invention.The preform 400 consists of a neck portion 402, a gate portion 406 and abody portion 404 extending between the neck portion 402 and the gateportion 406. The neck portion 402 and the body portion 404 can beimplemented in a substantially similar manner to the neck portion 102and the gate portion 106 of the preform 100 of FIG. 1.

The gate portion 406 is associated with a substantially conical shapethat terminates in a vestige portion 408. It is worthwhile noting thatthe vestige portion 408 delimits a lower terminal point of the conicalshape of the gate portion 406. Size of the vestige portion 408substantially corresponds to size of an orifice of a hot runner nozzle(not depicted).

Within the embodiment of FIG. 4, the gate portion 406 is associated withan internal curvature section 410, which is shown in an exaggerated viewin FIG. 4. It is worthwhile noting that within the embodiment of FIG. 4,the gate portion 406 is associated with a substantially non-uniform wallthickness. More specifically, wall thickness is comparatively higheraround the internal curvature section 410. It is also worthwhile notingthat even though the internal curvature section 410 is located on aninternal surface opposite of the vestige portion 408 in the embodimentof FIG. 4, in other non-limiting embodiments of the present invention asimilar curvature section can be located at other points (on theinternal surface or an external surface) of the gate portion 406. Anexample of this alternative placement may include, but is not limitedto, to a location (on the internal surface or the external surface)where the gate portion 406 meets the body portion 404, the locationbeing depicted in FIG. 4 at 420.

With reference to FIG. 6, there is depicted a mold stack 600 implementedaccording to a non-limiting embodiment of the present invention. Withinthe illustration being presented herein, the mold stack 600 isconfigured to produce the preform 300 of FIG. 3. It is, however,expected that suitable modifications can be made by those of ordinaryskill in the art to the mold stack 600 to produce the preform 400 ofFIG. 4.

The mold stack 600 comprises a core insert 602, a split mold insert pair604, a cavity insert 606 and a gate insert 608. In use, the core insert602, the split mold insert pair 604, the cavity insert 606 and the gateinsert 608 define a molding cavity 609, into which molding material(such as plasticized PET or other suitable molding material) can beinjected to form the preform 300.

With continued reference to FIG. 6 and with brief reference to FIG. 7,the core insert 602 is configured to define, in use, an internal surfaceof the preform 300. To that extent, the core insert 602 comprises afirst cavity defining portion 603 configured to define a portion of themolding cavity 609 and an attachment portion 601 configured forattachment to a core plate (not depicted). In the embodiment depictedherein, the attachment portion 601 can be further configured to define aportion of the molding cavity 609. In some embodiments of the presentinvention, the attachment portion 601 can be implemented as a lock ring.It should be noted that even though within the specific non-limitingembodiment being depicted herein, the first cavity defining portion 603and the attachment portion 601 are implemented as structurally separateelements, in alternative non-limiting embodiments of the presentinvention, they can be implemented differently. For example, inalternative non-limiting embodiments of the present invention, the coreinsert 602 can be implemented without the lock ring and the like.

The first cavity defining portion 603 comprises a gate defining portion610. More specifically, the gate defining portion 610 has asubstantially conical shape. Within some embodiments of the presentinvention, the gate defining portion 610 can be machined. However, inalternative non-limiting embodiments, other standard manufacturingmethods can be used, such as cutting operation, milling operation orgrinding operation.

With continued reference to FIG. 6, the split mold insert pair 604 isconfigured to define, in use, a portion of an external surface of thepreform 300 and, more specifically, a portion of an external surface ofthe neck portion 302 of the preform 300. The cavity insert 606 isconfigured to define, in use, a portion of an external surface of thepreform 300 and, more specifically, a portion of an external surface ofthe body portion 304 of the preform 300.

With continued reference to FIG. 6 and with brief reference to FIG. 8,the gate insert 608 is configured to define, in use, a portion of anexternal surface of the preform 300. To that extent, the gate insert 608comprises a second cavity defining portion 612 configured to define aportion of an external surface of the gate portion 306 of the preform300. Shape of the second cavity defining portion 612 generallycorresponds to the above-described gate portion 306. More specifically,the second cavity defining portion 612 is associated with an invertedconical shape.

Within some embodiments of the present invention, the second cavitydefining portion 612 can be machined. However, in alternativenon-limiting embodiments, other manufacturing methods can be used, suchas but not limited to standard drilling tools, grilling operation andthe like.

The inverted conical shape of the second cavity defining portion 612terminates in an extremity 802, which substantially corresponds indiameter to an orifice (not separately numbered) of a nozzle receptacle804 of the gate insert 608 (the nozzle receptacle 804 being configuredto receive, in use, a hot runner nozzle (not depicted), which is omittedfrom the illustration for the sake of simplicity).

With reference to FIG. 9, a preform 900 implemented in accordance withanother non-limiting embodiment of the present invention is depicted.The preform 900 consists of a neck portion 902, a gate portion 906 and abody portion 904 extending between the neck portion 902 and the gateportion 906. The neck portion 902 and the body portion 904 can beimplemented in a substantially similar manner to the neck portion 102and the gate portion 106 of the preform 100 of FIG. 1.

The gate portion 906 is associated with a substantially conical shapethat terminates in a vestige portion 908. Within the embodiment of FIG.9, the conical shape of the gate portion 906 comprises a first cone 910and a second cone 912. Within these embodiments of the presentinvention, the first cone 910 is associated with a first angle “β” andthe second cone 912 is associated with a second angle “γ”, the secondangle “γ” being larger that the first angle “β”.

It is worthwhile noting that the vestige portion 908 delimits a lowerterminal point of the second cone 912 (as well, as the overall conicalshape of the gate portion 906). Size of the vestige portion 908substantially corresponds to size of an orifice of a hot runner nozzle(not depicted).

With reference to FIG. 10, there is depicted a portion of a mold stack1000 implemented according to a non-limiting embodiment of the presentinvention. Within the illustration being presented herein, the moldstack 1000 is configured to produce the preform 900 of FIG. 9. The moldstack 1000 can be substantially similar to the mold stack 600, but forthe specific differences discussed herein below.

Specifically, the mold stack 1000 comprises inter alia a core insert1002 and a gate insert 1008. The core insert 1002 is configured todefine, in use, an internal surface of the preform 900. To that extent,the core insert 1002 comprises a first cavity defining portion 1003configured to define a portion of a molding cavity 1009. The firstcavity defining portion 1003 comprises a gate defining portion 1010. Thegate defining portion 1010 comprises a first cone portion 1010 a and asecond cone portion 1010 b.

The gate insert 1008 is configured to define, in use, a portion of anexternal surface of the preform 900. To that extent, the gate insert1008 comprises a second cavity defining portion 1012. The second cavitydefining portion 1012 comprises a first cone segment 1012 a and a secondcone segment 1012 b. In use, the first cone portion 1010 a and thesecond cone segment 1012 b cooperate to define the aforementioned firstcone 910. Similarly, the second cone portion 1010 b and the first conesegment 1012 a cooperate, in use, to define the aforementioned secondcone 912.

It should be noted that even though FIG. 9 and FIG. 10 depict thepreform 900 and the mold stack 1000 for producing the preform 900, thepreform 900 having the gate portion 906 comprised of the first cone 910and the second cone 912, in alternative embodiments of the presentinvention, the gate portion 906 can be comprised of two or more cones.

Accordingly, according to embodiments of the present invention, there isprovided the mold stack 600, 1000 and, more specifically, the coreinsert 602, 1002 and the gate insert 608, 1008 configured to produce thepreform 300, 400, 900 that substantially homogenizes angle of refractionof at least some of the set of infrared light rays 206 during there-heating stage of the blow-molding process and/or minimizes amount ofmaterial used to fill at least a portion of the preform 300, 400, 900and/or increases the fill rate.

According to embodiments of the present invention, there is alsoprovided a method for producing at least a portion of the mold stack600, 1000. More specifically, there is provided a method for producingone or both of the core insert 602, 1002 and the gate insert 608, 1008.The method includes:

Selecting a shape for the gate portion 306, 406, 906 to be produced, theshape of the gate portion 306, 406, 906 so selected as to at leastsubstantially homogenize angle of refraction of at least some of the setof infrared light rays 206 used during re-heating stage of theblow-molding process and, consequently, efficiency of re-heating. Insome embodiments of the present invention, the selecting stepadditionally or alternatively includes, additionally, selecting theshape which also reduces weight of the molding material used and/orimproves fill rates. In some embodiments of the present invention, theso-selected shape comprises a cone shape or a shape comprised of one ormore cones.

Once the shape is selected, the method further includes manufacturingone or both of the core insert 602, 1002 and the gate insert 608, 1008.Manufacturing can be implemented by using known techniques, such as aComputer Numerically Controlled (CNC) machining and the like.

Even though embodiments of the present invention have been describedherein above using the cavity insert 606 and the gate insert 608implemented as structurally separate members, in alternativenon-limiting embodiments of the present invention, the cavity insert 606and the gate insert 608 can be implemented as a structurally integralinsert. Similarly, even though the preform 300, 400, 900 has beendescribed as one suitable for stretch-blow molding; in alternativenon-limiting embodiments of the present invention, the preform 300, 400,900 can be subjected to other types of blowing processes. Furthermore,even though certain portions of the mold stack 600, 1000 have beendescribed as inserts, in alternative embodiments of the presentinvention, these components can be implemented as structurally integralcomponents of the mold plates and, accordingly, within the instantdescription the term “insert” is meant to include structurally integralcomponents of the mold plates.

Operation of the mold stack 600 of FIG. 6 can be implemented in asubstantially similar manner to operation of the prior art mold stacks(not depicted) and, accordingly, only a brief description of theoperation of the mold stack 600 will be presented herein. It is expectedthat those of ordinary skill in the art will be able to adapt theseteachings for operation of the mold stack 1000 of FIG. 10. In FIG. 6,the mold stack 600 is shown in a mold closed position, within which itcan be maintained by cooperating platens (ex. a moveable and a fixedplatens) under tonnage applied by suitable means (such as, hydraulic,electric means and the like).

Within the mold closed configuration, molding material can be injectedinto the molding cavity 609 from a hot runner nozzle (not depicted)received within the nozzle receptacle 804. How the molding material isdistributed between an injection unit (not depicted) and the hot runnernozzle (not depicted) can be implemented in a conventional manner. Theso-injected molding material is then solidified by means of, forexample, coolant being circulated in or around the cavity insert 606,and/or in or around the gate insert 608, and/or in or around the splitmold insert pair 604 and/or within the core insert 602.

The mold stack 600 is then actuated into a mold-open position where thepreform 200, 400, 900 can be de-molded from within the molding cavity609. Typically, when the mold stack 600 begins to open, the preform 200,400, 900 stays on the core insert 602. The split mold insert pair 604 isactivated in a lateral direction (by any suitable means, such as cams,servo motors, etc.) to provide clearance for the neck portion 302, 402,902). Movement of the split mold insert pair 604 in an operationaldirection causes the preform 200, 400, 900 to be removed from the coreinsert 602. At this point, the mold stack 600 can be actuated into themold closed condition and a new molding cycle can commence.

Even though embodiments of the present invention have been describedwith reference to injection molding and the mold stack 600, 1000suitable for injection molding, this need not be so in every embodimentof the present invention. Accordingly, it is expected that teachings ofthe present invention can be adapted to other types of moldingoperations, such as extrusion molding, compression molding, compressioninjection molding and the like.

A technical effect of embodiments of the present invention may includeprovision of the preform 300, 400, 900 which substantially homogenizesangle of refraction of at least some of the set of infrared light rays206 during re-heating stage of the blow-molding process within the gateportion 306, 406, 906. This, in turn, may lead to increased re-heatingefficiency of the gate portion 306, 406, 906 of the preform 300, 400,900 at least partially due to more constant absorbance of the set ofinfrared light rays 206, which can be attributed at least partially tomore homogenous angle of refraction along the length of the gate insert608, 1008 and/or decreased level of reflection. Another technical effectof embodiments of the present invention may include provision of thepreform 300, 400, 900 which requires less material compared to thepreform 100. This, in turn, may lead to cost savings associated withsavings associated with raw materials. Another technical effect ofembodiments of the present invention may includes provision of the moldstack 600 for producing the preform 300, 400, 900; the mold stack 600providing less of a pressure drop within a portion of the molding cavity609, 1009 that defines the gate portion 306, 406, 906 of the preform300, 400, 900. This, in turn, may result in a faster fill process. Itshould be expressly understood that not all of the technical effectsneed to be realized in each and every embodiment of the presentinvention.

A particular technical effect associated with the increased re-heatingefficiency of some of the embodiments of the present invention is bestillustrated with reference to FIG. 5, which depicts a portion of thepreform 300 of FIG. 3 during the re-heating stage of the blow moldingprocess. More specifically, a portion of the gate portion 306 isdepicted. The source of energy 202 and the reflector 204 have beenomitted from the illustration of FIG. 5 for the sake of simplicity. Asis clearly shown in FIG. 5, angle of refraction in the gate portion 306is significantly homogenized and substantially no sub-set of rays(similar to the sub-set of infrared light rays 210) and, as such,re-heating efficiency is substantially maintained or improved in thegate portion 306. Accordingly, a final-shaped article (not depicted)that is produced (for example, by means of blow-molding) from thepreform 300, 400, 900 can be said to have a stretched gate area thatsuffers from less internal stress due, at least partially, to betterre-heating efficiency.

Accordingly, it can be said that the preform 300, 400, 900 implementedin accordance with embodiments of the present invention, is associatedwith a shape that substantially homogenizes angle of refraction of atleast some of the set of infrared light rays 206 (or other types ofrays) around the gate portion 306, 406, 906 during the re-heating stageof the stretch-blow molding process.

Description of the non-limiting embodiments of the present inventionsprovides examples of the present invention, and these examples do notlimit the scope of the present invention. It is to be expresslyunderstood that the scope of the present invention is limited by theclaims. The concepts described above may be adapted for specificconditions and/or functions, and may be further extended to a variety ofother applications that are within the scope of the present invention.Having thus described the non-limiting embodiments of the presentinvention, it will be apparent that modifications and enhancements arepossible without departing from the concepts as described. Therefore,what is to be protected by way of letters patent are limited only by thescope of the following claims:

1. A preform suitable for subsequent blow-molding comprising: a neckportion; a gate portion; and a body portion extending between said neckportion and said gate portion; the gate portion being associated with asubstantially conical shape.
 2. The preform of claim 1, wherein thesubstantially conical shape is selected such that to substantiallyhomogenize angle of refraction of rays used during a re-heating stage ofa blow-molding process.
 3. The preform of claim 1, wherein thesubstantially conical shape terminates in a vestige portion having asize that substantially corresponds to an orifice of a hot runnernozzle.
 4. The preform of claim 1, wherein the gate portion comprises asubstantially even wall thickness.
 5. The preform of claim 1, whereinthe gate portion comprises a substantially non-even wall thickness. 6.The preform of claim 1, wherein said substantially conical shapecomprises at least one internal curvature section.
 7. The preform ofclaim 6, wherein said at least one internal curvature section comprisesa single curvature section located on an internal surface proximate to avestige portion of the gate portion.
 8. The preform of claim 1, whereinthe substantially conical shape is associated with an angle definedbetween an imaginary central line and an internal surface of thesubstantially conical shape.
 9. The preform of claim 8, wherein saidangle is calculated as a function of a refraction index of a materialbeing used for forming the preform such that to substantially homogenizeangle of refraction of rays used during a re-heating stage of ablow-molding process.
 10. The preform of claim 8, wherein said angle iscalculated as a function of at least one of: (i) a refraction index of amaterial being used for forming the preform, (ii) a fill speed; and(iii) weight of material to be used such that to substantiallyhomogenize angle of refraction of rays used during a re-heating stage ofa blow-molding process.
 11. The preform of claim 1, wherein saidsubstantially conical shape comprises a first cone and a second cone.12. The preform of claim 11, wherein said first cone is associated witha first angle defined between an imaginary central line and an internalsurface of the substantially conical shape and said second cone isassociated with a second angle defined between the imaginary centralline and the internal surface of the substantially conical shape.
 13. Amold stack comprising: a core insert for defining an internal surface ofa preform; a split mold insert pair for defining an external surface ofa neck portion of the preform; a cavity insert for defining the externalsurface of a body portion of the preform; a gate insert for defining theexternal surface of a gate portion of the preform; the core insert andthe gate insert being configured to cooperate, in use, to define thegate portion of the preform having a first substantially conical shape.14. The mold stack of claim 13, wherein said core insert comprises afirst cavity defining portion and wherein said first cavity definingportion (603, 10003) comprises a gate defining portion which has asecond substantially conical shape.
 15. The mold stack (1000) of claim14, wherein said first substantially conical shape comprises a firstcone and a second cone and wherein said second substantially conicalshape comprises a first cone portion (1010 a) and a second cone portion(1010 b).
 16. The mold stack of claim 13, wherein said gate insertcomprises a second cavity defining portion and wherein said secondcavity defining portion (1012, 612) comprises a substantially invertedconical shape.
 17. The mold stack (1000) of claim 16, wherein said firstsubstantially conical shape comprises a first cone and a second cone andwherein said substantially inverted conical shape comprises a first conesegment (1012 a) and a second cone segment (1012 b).
 18. The mold stackof claim 13, wherein said cavity insert and said gate insert areintegrally made.
 19. A core insert for defining, in use, a portion of apreform, the preform including a neck portion, a gate portion and a bodyportion extending therebetween, the core insert comprising: a firstcavity defining portion having a gate defining portion which hassubstantially conical shape, the substantially conical shape so selectedsuch that to substantially homogenize angle of refraction of rays usedduring a re-heating stage of a blow-molding process of the preformwithin the gate portion.
 20. A gate insert for defining, in use, aportion of a preform, the preform including a neck portion, a gateportion and a body portion extending therebetween, the gate insertcomprising: a second cavity defining portion having a substantiallyinverted conical shape, the substantially inverted conical shape soselected such that to substantially harmonize angle of refraction ofrays used during a re-heating stage of a blow-molding process of thepreform within the gate portion (306, 406,
 906. 21. A method ofproducing at least a portion of a mold stack comprising: selecting ashape for a gate portion of a preform suitable for blow-molding, theshape so selected as to at least substantially homogenize angle ofrefraction of at least some of a set of rays during re-heating stage ofa blow-molding process; manufacturing the at least a portion of the moldstack to include the shape.
 22. The method of claim 21, wherein said atleast a portion comprises at least one of a core insert and a gateinsert.
 23. The method of claim 21, wherein said selecting comprisesdetermining the shape based on at least one of a refraction index of amolding material used, fill rate and weight of molding material to beused.
 24. The method of claim 21, wherein the shape comprises asubstantially conical shape.
 25. A final-shaped article produced fromthe preform as recited in claim
 1. 26. A preform suitable for subsequentblow-molding comprising: a neck portion; a gate portion; and a bodyportion extending between said neck portion and said gate portion; thegate portion being associated a shape so selected such that tosubstantially homogenize angle of refraction of rays used during are-heating stage of a blow-molding process.